Safety and feasibility of intravenous sotalol loading for the prevention of ventricular arrhythmias.

BACKGROUND: The use of intravenous (IV) sotalol loading following recent U.S. Food and Drug Administration (FDA) approval of a 1-day loading protocol has reduced the obligatory 3-day hospital stay for sotalol initiation when given orally. Several studies have recently demonstrated the safety and feasibility of IV loading for patients with atrial arrhythmias. However, there is a paucity of data on the feasibility and safety of IV sotalol loading for patients with ventricular arrhythmias. This study aims to assess the safety, feasibility, and length of stay (LOS) outcomes of IV sotalol loading for the prevention of ventricular arrhythmias. METHODS: A retrospective analysis was performed of all patients undergoing IV sotalol loading and oral sotalol initiation for ventricular arrhythmias, or IV sotalol loading for atrial arrhythmias between August 2021 and December 2023 at Northwestern University. Baseline characteristics, success of sotalol initiation/loading, changes in heart rate (HR) and QT/QTc, safety, and LOS were compared between patients undergoing sotalol loading/initiation for ventricular arrhythmias (IV vs. PO) and between patients undergoing IV sotalol loading for ventricular arrhythmias vs. for atrial arrhythmias. RESULTS: A total of 28 patients underwent sotalol loading/initiation for ventricular arrhythmias (N = 15 IV and N = 13 PO) and 41 patients underwent IV sotalol loading for atrial arrhythmias. Baseline characteristics of congestive heart failure history and left ventricular ejection fraction were worse in the ventricular arrhythmias group. There was no significant difference in the successful completion of IV sotalol loading for ventricular arrhythmias compared to oral sotalol initiation for ventricular arrhythmias or IV sotalol loading for atrial arrhythmias (86.7% vs. 92.3% vs. 90.2%, p = 0.88). There was a significant increase in ΔQTc following IV sotalol infusion for ventricular arrhythmias compared to following PO sotalol initiation for ventricular arrhythmias (46.4 ± 29.2 ms vs. 8.9 ± 32.6 ms, p = 0.004) and following IV sotalol infusion for atrial arrhythmias (46.4 ± 29.2 ms vs. 24.0 ± 25.1 ms, p = 0.018). ΔHR following IV sotalol infusion for ventricular arrhythmias was similar to ΔHR following PO sotalol initiation for ventricular arrhythmias and ΔHR following IV sotalol infusion for atrial arrhythmias (- 7.5 ± 8.7 bpm vs. - 8.5 ± 13.9 bpm vs. - 8.3 ± 13.2 bpm, p = 0.87). There were no significant differences in discontinuation for QTc prolongation (6.7% vs. 1.7% vs. 2.4%, p = 0.64) and bradycardia (13.3% vs. 7.7% vs. 9.8%, p = 0.88) between IV sotalol loading for ventricular arrhythmias, PO sotalol initiation for ventricular arrhythmias, and IV sotalol loading for atrial arrhythmias. There were no instances of hypotension, life-threatening ventricular arrhythmias, heart failure, or death. Length of stay was significantly shorter for IV sotalol loading compared to PO sotalol initiation for ventricular arrhythmias (1.1 ± 0.36 days vs. 4.2 ± 1.0 days, p < 0.0001). CONCLUSION: IV sotalol loading appears feasible and safe for use in ventricular arrhythmias and results in a decreased length of stay. Despite increased comorbidities and greater increase in QTc interval following IV sotalol infusion in the ventricular arrhythmias group, there were no significant differences in successful completion of loading or adverse outcomes when compared to PO sotalol initiation for ventricular arrhythmias and IV loading for atrial arrhythmias.

Patient-reported quality of life and acceptance of the extravascular implantable cardioverter-defibrillator: Results from pivotal study.

INTRODUCTION: The pivotal study of the extravascular implantable cardioverter-defibrillator (EV ICD) recently demonstrated primary efficacy and safety endpoints comparable to previous ICD systems. Patient experience with this novel device has not been reported. The current study examined the standardized patient-reported outcome (PRO) metrics of quality of life (QOL) and patient acceptance of the device. METHODS: The EV ICD Pivotal Study was a prospective, single-arm, nonrandomized, global, premarket approval trial. Patients completed the 12-Item Short Form Survey (SF-12) QOL surveys at baseline and at 6 months following implant. Additionally, patients completed the Florida Patient Acceptance Survey (FPAS) QOL survey at 6 months. RESULTS: From baseline to 6 months, patients within the EV ICD Pivotal Study (n = 247) reported statistically significant SF-12 improvements in physical QOL (45.4 ± 9.4 vs. 46.8 ± 9.1 respectively, p = .020) and no changes in mental QOL (49.3 ± 10.4 vs. 50.5 ± 9.7, p = .061). No differences were noted by sex, atrial fibrillation, or the experience of ICD shock. EV ICD patients reported better total FPAS patient acceptance of their ICD than TV-ICD or S-ICD patients using historical norms comparisons (80.4 ± 15.7 vs. 70.2 ± 17.8, p < .0001 for S-ICD and 73.0 ± 17.4, p = .004 for TV-ICD). CONCLUSION: The initial PROs for EV ICD patients indicated that patients had improvements in physical QOL from baseline to 6-month follow-up and markedly better overall acceptance of their ICD compared to a previous study with S-ICD and TV-ICD data. These initial results suggest that the EV ICD is evaluated positively by patients.

The clinical and economic impact of extended battery longevity of a substernal extravascular implantable cardioverter defibrillator.

INTRODUCTION: The extravascular implantable cardioverter defibrillator (EV ICD) has extended projected battery longevity compared to the subcutaneous implantable cardioverter defibrillator (S-ICD). This study used modeling to characterize the need for generator changes, long-term complications, and overall costs for both the EV ICD and S-ICD in healthcare systems of various countries. METHODS: Battery longevity data were modeled using a Markov model from averages reported in device labeling for the S-ICD and with engineering estimates based on real life usage from EV ICD Pivotal Study patient data to introduce variability. Clinical demographic data were derived from published literature. The primary outcomes were defined as the number of generator replacement surgeries, complications, and total healthcare system costs due to battery depletion over the expected lifetime of patients receiving EV ICD or S-ICD therapy. RESULTS: Average modeled battery longevity was determined to be 7.3 years for the S-ICD versus 11.8 years for the EV ICD. The probability of a complication after a replacement procedure was 1.4%, with an operative mortality rate of 0.02%. The use of EV ICD was associated with 1.4-1.6 fewer replacements on average over an expected patient lifetime as compared to S-ICD and a 24.3%-26.0% reduction in cost. A one-way sensitivity analysis of the model for the US healthcare system found that use of an EV ICD resulted in a reduction in replacement surgeries of greater than 1 (1.1-1.6) along with five-figure cost savings in all scenarios ($18 602-$40 948). CONCLUSION: The longer projected battery life of the EV ICD has the potential to meaningfully reduce long-term morbidity and healthcare resources related to generator changes from the perspective of multiple diverse healthcare systems.

Does asymptomatic atrial fibrillation exist?

Atrial fibrillation (AF) is currently defined as symptomatic by asking patients if they are aware of when they are in AF and if they feel better in sinus rhythm. However, this approach of defining AF as symptomatic and asymptomatic fails to adequately consider the adverse effects of AF in patients who are unaware of their rhythm including progression from paroxysmal to persistent AF, and the development of dementia, stroke, sinus node dysfunction, valvular regurgitation, ventricular dysfunction, and heart failure. Labeling these patients as asymptomatic falsely suggests that their AF requires less intense therapy and puts into question the notion of truly asymptomatic AF. Because focusing on patient awareness ignores other important consequences of AF, clinical endpoints that are independent of symptoms are being developed. The concept of AF burden has more recently been used as a clinical endpoint in clinical trials as a more clinically relevant endpoint compared to AF-related symptoms or time to first recurrence, but its correlation with symptoms and other clinical outcomes remains unclear. This review will explore the impact of AF on apparently asymptomatic patients, the use of AF burden as an endpoint for AF management, and potential refinements to the AF burden metric. The review is based on a presentation by the senior author during the 2023 16th annual European Cardiac Arrhythmia Society (ECAS) congress in Paris, France.

Use of Atrial Fibrillation Electrograms and T1/T2 Magnetic Resonance Imaging to Define the Progressive Nature of Molecular and Structural Remodeling: A New Paradigm Underlying the Emergence of Persistent Atrial Fibrillation.

BACKGROUND: The temporal progression states of the molecular and structural substrate in atrial fibrillation (AF) are not well understood. We hypothesized that these can be detected by AF electrograms and magnetic resonance imaging parametric mapping. METHODS AND RESULTS: AF was induced in 43 dogs (25-35 kg, ≥1 year) by rapid atrial pacing (RAP) (3-33 weeks, 600 beats/min), and 4 controls were used. We performed high-resolution epicardial mapping (UnEmap, 6 atrial regions, both atria, 130 electrodes, distance 2.5 mm) and analyzed electrogram cycle length, dominant frequency, organization index, and peak-to-peak bipolar voltage. Implantable telemetry recordings were used to quantify parasympathetic nerve activity over RAP time. Magnetic resonance imaging native T1, postcontrast T1, T2 mapping, and extracellular volume fraction were assessed (1.5T, Siemens) at baseline and AF. In explanted atrial tissue, DNA oxidative damage (8-hydroxy-2'-deoxyguanosine staining) and percentage of fibrofatty tissue were quantified. Cycle length and organization index decreased (R=0.5, P<0.05; and R=0.5, P<0.05; respectively), and dominant frequency increased (R=0.3, P n.s.) until 80 days of RAP but not thereafter. In contrast, voltage continued to decrease throughout the duration of RAP (R=0.6, P<0.05). Parasympathetic nerve activity increased following RAP and plateaued at 80 days. Magnetic resonance imaging native T1 and T2 times increased with RAP days (R=0.5, P<0.05; R=0.6, P<0.05) in the posterior left atrium throughout RAP. Increased RAP days correlated with increasing 8-hydroxy-2'-deoxyguanosine levels and with fibrosis percentage (R=0.5, P<0.05 for both). CONCLUSIONS: A combination of AF electrogram characteristics and T1/T2 magnetic resonance imaging can detect early-stage AF remodeling (autonomic remodeling, oxidative stress) and advanced AF remodeling due to oxidative stress and fibrosis.

Comparison of transseptal puncture using a dedicated RF wire versus a mechanical needle with and without electrification in an animal model.

INTRODUCTION: Mechanical force to achieve transseptal puncture (TSP) using a standard needle may lead to overshooting and injury, and can potentially be avoided using a radiofrequency (RF)-powered needle or wire. Applying electrocautery to needles and guidewires as an alternative to purpose-built RF systems has been associated with safety risks, such as tissue coring and thermal damage. The commercially available AcQCross needle-dilator system (Medtronic) features a sharp open-ended needle for mechanical puncture, as well as a built-in connector to enable energy delivery for RF puncture. This investigation compares the safety and efficacy of the AcQCross needle to the dedicated VersaCross RF wire system and generator (Baylis Medical/Boston Scientific). METHODS: In an ex vivo porcine model, VersaCross wire punctures were performed using 1 s, constant mode (approx. 10 W) with maximum two attempts. AcQCross punctures were performed by applying energy for 2 s using a standard electrosurgical generator at 10 W (max. five attempts), 20 W (max. two attempts), and 30 W (max. two attempts). Efficacy was assessed in terms of puncture success and a number of energy applications required for TSP. Safety was assessed quantitatively as force required for TSP, energy required to puncture, and incidence of tissue coring, as well as by qualitative assessment of puncture sites. Additional qualitative observation of tissue cores and debris were obtained from TSP performed in live swine. RESULTS: RF TSP was 100% successful using the VersaCross wire with 1.0 ± 0.0 attempts. When power was used with the AcQCross needle, it failed to puncture at low (10 and 20 W) power settings; TSP was achieved with 30 W of energy with 91% success using 1.53 ± 0.51 attempts (p < .05 vs. VC) with greater variability (F1,33 = 9223.5, p < .0001). Compared to RF puncture using the VersaCross system, mechanical puncture, alone, using the AcQcross needle required six times more force (8 mm additional forward device displacement) to perforate the septum. Qualitative assessment of puncture sites revealed larger defects and more tissue charring with the AcQCross needle at 30 W compared to punctures with VersaCross wire. Tissue coring with the open-ended AcQCross needle was observed in vivo and measured to occur in 57% of punctures using the ex vivo model; no coring was observed with the closed-tip VersaCross wire. CONCLUSIONS: The AcQCross needle frequently required higher energy of 30 W to achieve RF TSP and was associated with tissue coring and charring, which have been, previously, reported when electrifying a standard open-ended mechanical needle or guidewire. These findings may limit safety and effectiveness compared to the VersaCross system.

Percutaneous coronary intervention for ventricular fibrillation in the setting of an anomalous right coronary artery.

We present a case of a quadriplegic male who developed ventricular fibrillation associated with an anomalous aortic origin of the right coronary artery. Successful revascularization was achieved with percutaneous coronary intervention. This case highlights the application of an unconventional approach to resolve ischemia in a patient with prohibitive surgical risk.

Persistent and Recurrent Device-Related Thrombus After Left Atrial Appendage Closure: Incidence, Predictors, and Outcomes.

BACKGROUND: Scarce data exist on the evolution of device-related thrombus (DRT) after left atrial appendage closure (LAAC). OBJECTIVES: This study sought to assess the incidence, predictors, and clinical impact of persistent and recurrent DRT in LAAC recipients. METHODS: Data were obtained from an international multicenter registry including 237 patients diagnosed with DRT after LAAC. Of these, 214 patients with a subsequent imaging examination after the initial diagnosis of DRT were included. Unfavorable evolution of DRT was defined as either persisting or recurrent DRT. RESULTS: DRT resolved in 153 (71.5%) cases and persisted in 61 (28.5%) cases. Larger DRT size (OR per 1-mm increase: 1.08; 95% CI: 1.02-1.15; P = 0.009) and female (OR: 2.44; 95% CI: 1.12-5.26; P = 0.02) were independently associated with persistent DRT. After DRT resolution, 82 (53.6%) of 153 patients had repeated device imaging, with 14 (17.1%) cases diagnosed with recurrent DRT. Overall, 75 (35.0%) patients had unfavorable evolution of DRT, and the sole predictor was average thrombus size at initial diagnosis (OR per 1-mm increase: 1.09; 95% CI: 1.03-1.16; P = 0.003), with an optimal cutoff size of 7 mm (OR: 2.51; 95% CI: 1.39-4.52; P = 0.002). Unfavorable evolution of DRT was associated with a higher rate of thromboembolic events compared with resolved DRT (26.7% vs 15.1%; HR: 2.13; 95% CI: 1.15-3.94; P = 0.02). CONCLUSIONS: About one-third of DRT events had an unfavorable evolution (either persisting or recurring), with a larger initial thrombus size (particularly >7 mm) portending an increased risk. Unfavorable evolution of DRT was associated with a 2-fold higher risk of thromboembolic events compared with resolved DRT.

Impact of Age on Subcutaneous Implantable Cardioverter-Defibrillator in a Large Patient Cohort: Mid-Term Follow-Up.

BACKGROUND: The subcutaneous implantable cardioverter-defibrillator (S-ICD) is an accepted alternative to transvenous (TV) ICD to provide defibrillation therapy to treat life-threatening ventricular tachyarrhythmias in high-risk patients. S-ICD outcomes by age group have not been reported. OBJECTIVES: In this study, the authors sought to report S-ICD outcomes in different age groups in a multicenter S-ICD post-approval study (PAS) involving the largest cohort of patients ever reported. METHODS: Patients were prospectively enrolled in the S-ICD PAS and stratified based on age: young, aged 15-34 years; adult, aged 35-69 years; and elderly, aged ≥70 years. Patient characteristics and clinical outcomes through 3 years of follow up after implantation were compared. RESULTS: The S-ICD PAS enrolled 1,637 patients. Elderly patients were more likely to receive an S-ICD as a replacement of a TV-ICD (15.1% elderly vs 12.3% adult vs 7.4% young). Secondary prevention indication decreased with age (32.7% young vs 22.2% adult vs 20.5% elderly). Mortality rate was significantly higher in the elderly group (24.0% elderly vs 13.0% adult vs 7.4% young; P < 0.0001), whereas the complication rate did not differ significantly (12.3% young vs 11.3% adult vs 8.1% elderly). Rates of appropriate shock (12.7% young vs 13.0% adult vs 13.8% elderly) and inappropriate shock (7.8% young vs 9.1% adult vs 8.8% elderly) rates did not differ between groups (P = 0.96 and P = 0.98, respectively). CONCLUSIONS: Implant complications and appropriate and inappropriate shock rates were similar among age groups. S-ICD for secondary prevention was more common in the young group. Replacing a TV-ICD for an S-ICD increases with age. (S-ICD System Post-Approval Study; NCT01736618).

Postapproval Study of a Subcutaneous Implantable Cardioverter-Defibrillator System.

BACKGROUND: The subcutaneous implantable cardioverter-defibrillator (S-ICD) was developed to avoid complications related to transvenous implantable cardioverter-defibrillator (TV-ICD) leads. Device safety and efficacy were demonstrated previously with atypical clinical patients or limited follow-up. OBJECTIVES: The S-ICD PAS (Subcutaneous Implantable Cardioverter-Defibrillator System Post Approval Study) is a real-world, multicenter, registry of U.S. centers that was designed to assess long-term S-ICD safety and efficacy in a diverse group of patients and implantation centers. METHODS: Patients were enrolled in 86 U.S. centers with standard S-ICD indications and were observed for up to 5 years. Efficacy endpoints were first and final shock efficacy. Safety endpoints were complications directly related to the S-ICD system or implantation procedure. Endpoints were assessed using prespecified performance goals. RESULTS: A total of 1,643 patients were prospectively enrolled, with a median follow-up of 4.2 years. All prespecified safety and efficacy endpoint goals were met. Shock efficacy rates for discrete episodes of ventricular tachycardia or ventricular fibrillation were 98.4%, and they did not differ significantly across follow-up years (P = 0.68). S-ICD-related and electrode-related complication-free rates were 93.4% and 99.3%, respectively. Only 1.6% of patients had their devices replaced by a TV-ICD for a pacing need. Cumulative all-cause mortality was 21.7%. CONCLUSIONS: In the largest prospective study of the S-ICD to date, all study endpoints were met, despite a cohort with more comorbidities than in most previous trials. Complication rates were low and shock efficacy was high. These results demonstrate the 5-year S-ICD safety and efficacy for a large, diverse cohort of S-ICD recipients. (Subcutaneous Implantable Cardioverter-Defibrillator [S-ICD] System Post Approval Study [PAS]; NCT01736618).

Regions of Highly Recurrent Electrogram Morphology With Low Cycle Length Reflect Substrate for Atrial Fibrillation.

Traditional anatomically guided ablation and attempts to perform electrogram-guided atrial fibrillation (AF) ablation (CFAE, DF, and FIRM) have not been shown to be sufficient treatment for persistent AF. Using biatrial high-density electrophysiologic mapping in a canine rapid atrial pacing model of AF, we systematically investigated the relationship of electrogram morphology recurrence (EMR) (Rec% and CLR) with established AF electrogram parameters and tissue characteristics. Rec% correlates with stability of rotational activity and with the spatial distribution of parasympathetic nerve fibers. These results have indicated that EMR may therefore be a viable therapeutic target in persistent AF.

Validation of the SCALE-CryoAF risk model to predict very late return of atrial fibrillation after cryoballoon ablation.

BACKGROUND: To date, few risk models have been validated to predict recurrent atrial fibrillation (AF) >1 year after ablation. The SCALE-CryoAF score was previously derived to predict very late return of AF (VLRAF) >1 year following cryoballoon ablation (CBA), with strong predictive ability. In this study, we aim to validate the SCALE-CryoAF score for VLRAF after CBA in a novel patient cohort. METHODS: Retrospective analysis of a prospectively maintained single-center database was performed. Inclusion criteria were pulmonary vein isolation using CBA 2017-2020. Exclusion criteria included prior ablation, <1-year follow-up, lack of pre-CBA echocardiogram, additional ablation lesion sets, and documented AF recurrence 90-365 days post-CBA. The area under the curve (AUC) of SCALE-CryoAF was compared to the derivation value and other established risk models. RESULTS: Among 469 CBA performed, 241 (61% male, 62.8 ±11.7 years old) cases were included in analysis. There were 37 (15.4%) patients who developed VLRAF. Patients with VLRAF had a higher SCALE-CryoAF score (VLRAF 5.4 ± 2.7; no VLRAF 3.1 ± 2.9; p<0.001). SCALE-CryoAF was linearly associated with VLRAF (y=14.35x-11.72, R2=0.99), and a score > 5 had a 32.7% risk of VLRAF. The SCALE-CryoAF risk model predicted VLRAF with an AUC of 0.74, which was similar to the derivation value (AUCderivation: 0.73) and statistically superior to MB-LATER, CHA2DS2-VASc, and CHADS2 scores. CONCLUSIONS: The current analysis validates the ability of SCALE-CryoAF to predict VLRAF after CBA in a novel patient cohort. Patients with a high SCALE-CryoAF score should be monitored closely for recurrent AF >1 year following CBA.

Implementation of an intravenous sotalol initiation protocol: Implications for feasibility, safety, and length of stay.

INTRODUCTION: Oral sotalol initiation requires a multiple-day, inpatient admission to monitor for QT prolongation during loading. A 1-day intravenous (IV) sotalol loading protocol was approved by the United States Food and Drug Administration in March 2020, but limited data on clinical use and administration currently exists. This study describes implementation of an IV sotalol protocol within an integrated health system, provides initial efficacy and safety outcomes, and examines length of stay (LOS) compared with oral sotalol initiation. METHODS: IV sotalol was administered according to a prespecified initiation protocol to adult patients with refractory atrial or ventricular arrhythmias. Baseline characteristics, safety and feasibility outcomes, and LOS were compared with patients receiving oral sotalol over a similar time period. RESULTS: From January 2021 to June 2022, a total of 29 patients (average age 66.0 ± 8.6 years, 27.6% women) underwent IV sotalol load and 20 patients (average age 60.4 ± 13.9 years, 65.0% women) underwent oral sotalol load. The load was successfully completed in 22/29 (75.9%) patients receiving IV sotalol and 20/20 (100%) of patients receiving oral sotalol, although 7/20 of the oral sotalol patients (35.0%) required dose reduction. Adverse events interrupting IV sotalol infusion included bradycardia (seven patients, 24.1%) and QT prolongation (three patients, 10.3%). No patients receiving IV or oral sotalol developed sustained ventricular arrhythmias before discharge. LOS for patients completing IV load was 2.6 days shorter (mean 1.0 vs. 3.6, p < .001) compared with LOS with oral load. CONCLUSION: IV sotalol loading has a safety profile that is similar to oral sotalol. It significantly shortens hospital LOS, potentially leading to large cost savings.

Subcutaneous implantable cardioverter-defibrillator implantation position predicts successful defibrillation in obese and non-obese patients.

BACKGROUND: Subcutaneous implantable cardioverter-defibrillators (S-ICD) are an alternative to transvenous ICDs for patients without a need for cardiac pacing. Obese patients have been proposed to be at higher risk for conversion failure with S-ICDs due to subcutaneous fat underneath the device. Optimal device positioning may promote equivalent outcomes between obese and non-obese patients by minimizing the effects of excess adipose tissue. METHODS: A retrospective analysis of patients undergoing defibrillation testing at the time of S-ICD implantation was performed. The primary endpoint was the rate of successful conversion of ventricular fibrillation (VF) at the time of implant. The secondary endpoint was shock impedance. RESULTS: A total of 184 patients were included in the study. The rate of successful conversion of VF was 90.3% for obese patients (n = 72) and 96.4% for non-obese patients (n = 112) (p = 0.086). Compared to non-obese patients, obese patients had a higher mean PRAETORIAN score (78.5 ± 58.1 vs. 48.8 ± 35.5, p < 0.001) and higher measured mean impedance (82.0 ohms ± 26.5 vs. 69.8 ohms ± 19.3, p < 0.001). Patients with a PRAETORIAN score < 90 all had successful defibrillation testing regardless of BMI. CONCLUSIONS: In this study, a PRAETORIAN score < 90 was associated with a 100% success rate of defibrillation testing following S-ICD implantation regardless of patient body mass index (BMI). Thus, the impact of obesity on impedance and the risk of failed shocks may be minimized with close attention to implantation technique to achieve a low PRAETORIAN score.